1. Field of the Invention
The present invention relates to a polymer and a positive-tone radiation-sensitive resin composition.
2. Discussion of the Background
A chemically-amplified positive-tone radiation-sensitive resin composition is a composition generating an acid when exposed to deep ultraviolet rays having a wavelength of 250 nm or less (e.g. a KrF excimer laser and an ArF excimer laser) or electron beams and causing a solubility rate difference between an exposed area and a non-exposed area in a developing solution by a chemical reaction catalyzed by the acid, thereby forming a resist pattern on a substrate.
For example, when a KrF excimer laser (wavelength: 248 nm) is used as a light source, a chemically-amplified radiation-sensitive resin composition containing a polymer having a poly(hydroxystyrene) (hereinafter referred to from time to time as “PHS”) skeleton having a small absorbance of a light at a wavelength of 248 nm is used. An excellent pattern can be formed at high sensitivity and high resolution by using such a composition.
However, when a shorter wavelength light such as an ArF excimer laser (wavelength: 193 nm) is used as a light source in order to form a more minute pattern, it is difficult to use an aromatic compound such as PHS which has a larger absorbance of a light at a wavelength of 193 nm.
Therefore, as a lithography material using an ArF excimer laser as a light source, a resin composition containing a polymer having an alicyclic hydrocarbon skeleton, particularly a lactone skeleton repeating unit which does not have larger absorbance of a light at 193 nm wavelength has been used.
Japanese Patent Application Publications (KOKAI) No. 2002-201232, No. 2002-145955, No. 2003-84436, No. 2003-322963, and No. 2005-316136 disclose related-art technologies.